A biopsy of human liquid, such as urine, saliva, pleural effusion, and cerebrospinal liquid, is the sampling and analysis of the bioliquid. With isolation and study of specific biomarkers in the bioliquid, liquid biopsy can be used as a diagnostic and monitoring tool for diseases such as cancer, with the added benefit of being largely non-invasive. The specific biomarkers in the bioliquid include circulating tumor DNA (ctDNA), circulating tumor cells (CTCs), and microvesicles (i.e. exosomes). The study of CTCs and exosomes is helpful to obtain information from different perspectives, and thus improve the precision of liquid biopsy.
The existing approaches to isolation and purification of CTCs and exosomes include centrifuging, testing immuno-affinities, and filtering. However, centrifuging may cause mechanical damages to CTCs and exosomes, and is limited in throughput for clinical applications. Immuno-affinity relies on antibodies which results in higher cost, and the release process after immune-affinity may reduce the viability of CTCs and exosomes. Filtering is low cost and has high throughput, and the biological sample after filtration has good viability. However, clogging of the filtration membrane usually happens during filtration, which can decrease the isolation efficiency and purity of CTCs and exosomes.
Therefore, there is room for improvement in the art.